| Manhattan. | Weehawken. | Total yardage. | |
|---|---|---|---|
| Cubic yards placed | 14,706½ | 3,723 | 18,429½ |
| Labor. | Average Cost per Cubic Yard. | ||
| Surface transport | $0.31 | $1.43 | $0.54 |
| Superintendence and general labor at point of work | 0.31 | 1.31 | 0.51 |
| Mixing | 0.52 | 0.56 | 0.53 |
| Laying | 1.38 | 1.45 | 1.39 |
| Tunnel transport | 1.30 | 1.47 | 1.34 |
| Cleaning | 0.21 | 0.17 | |
| Forms: erecting and removal | 1.58 | 1.51 | 1.56 |
| Total labor | $5.61 | $7.73 | $6.04 |
| Material. | |||
| Cement | $2.30 | $2.22 | $2.28 |
| Sand | 0.34 | 0.40 | 0.36 |
| Stone | 0.91 | 0.61 | 0.85 |
| Lumber for forms | 0.47 | 0.45 | 0.47 |
| Sundry tunnel supplies | 0.16 | 0.17 | 0.16 |
| Total materials | $4.18 | $3.85 | $4.12 |
| Plant running | $0.44 | $0.44 | $0.44 |
| Surface labor, repairs and maintenance | 0.25 | 1.24 | 0.44 |
| Field office administration | 0.50 | 1.72 | 0.75 |
| Total field charges | $10.98 | $14.98 | $11.79 |
| Plant depreciation | $0.62 | $1.57 | $0.81 |
| Chief office administration | 0.24 | 0.31 | 0.25 |
| Total average cost per cubic yard | $11.84 | $16.86 | $12.85 |
| Cost of Miscellaneous Items in Concrete. | |||
| Manhattan. | Weehawken. | Average. | |
| Cubic yards | 14,706½ | 3,723 | 18,429½ |
| Amount, in dollars | $6,184.83 | $1,756.79 | $7,941.62 |
| Unit cost | 0.42 | 0.47 | 0.43 |
The 24-ft. 6-in. tunnel adjoining the Terminal Station-West was water-proofed by a surface-rendering method which, up to the present time, has been satisfactory. Generally speaking, the arches of the Land Tunnels, though not dripping with water, are the dampest parts of the whole structure from Tenth Avenue to Weehawken, and it would seem as if some form of water-proofing over these arches would have been a distinct advantage.
There was no difficulty in applying the water-proofing on the side-walls, after a little experience had been gained as to the best methods. The specifications required the sand-wall to be covered with alternate layers of coal-tar pitch and felt, seven layers of the former and six layers of the latter, the felt to be of Hydrex brand or other equally satisfactory to the engineer. The pitch was to be straight-run, coal-tar pitch which would soften at 60° Fahr., and melt at 100° Fahr., being a grade in which distillate oils, distilled from it, should have a specified gravity of 1.105. The pitch was to be mopped on the surface to a uniform thickness of 1/16 in., and a covering of felt, previously mopped with pitch, was to be applied immediately. The sheets were to lap not less than 4 in. on cross-joints and 12 in. on longitudinal joints, and had to adhere firmly to the pitch-covered surface. This layer was then to be mopped, and another layer placed, and so on until all the layers were in place. This water-proofing was to extend from the bottom of the cable conduits to the springing of the brick arch. Where sub-track conduits were used, these were to be surrounded with their own water-proofing. The work was carried out as specified; the sand-walls were not rendered, but were built smooth enough to apply the water-proofing directly to them. They were dried with gasoline torches before the application of the pitch, and in very wet sections grooves were cut to lead the water away.
The first attempts were with the felt laid in horizontal strips. This ended very disastrously, as the pitch could not sustain the weight of the felt, and the whole arrangement slipped down the wall. The felt was then laid vertically, being tacked to a piece of horizontal scantling at the top of the sand-wall and also held by a row of planks braced against it at about half its height. A layer of porous brick was laid as a drain along the base of the water-proofing, covered by a single layer of felt to prevent it from becoming choked with concrete.
The water-proofing of the sub-track conduits was troublesome, as the numerous layers and the necessity for preserving the proper laps in both directions between adjacent layers made the whole thing a kind of Chinese puzzle. Various modifications, to suit local conditions, were made from time to time. Conduits outside the general outline of the tunnel are difficult to excavate, to lay, and to water-proof, and should be avoided wherever possible.
The usual force in water-proofing consisted of a foreman, at $3.50 per day, and nine laborers at $1.75 per day. These men not only laid the water-proofing, but transported the materials, heated the pitch, and cut up the rolls of felt. In general, two men transported material, one tended the heater, and the other six worked in pairs, two preparing the surface of the concrete sand-wall, two laying pitch, and two laying felt.
The cost of the water-proofing operation was about as shown in [Table 14].
TABLE 14.— Cost of Water-Proofing, in Dollars per Square Foot.
| Manhattan. | Weehawken. | Total. | |
|---|---|---|---|
| Square feet covered | 47,042 | 13,964 | 60,736 |
| Average cost per square foot. | |||
| Labor | $0.07 | $0.07 | $0.07 |
| Material | 0.12 | 0.09 | 0.11 |
| Total field charges | $0.19 | $0.16 | $0.18 |
| Chief office and plant depreciation | 0.01 | 0.03 | 0.02 |
| Total average cost | $0.20 | $0.19 | $0.20 |